Overseed your lawn in the fall after killing weeds in late summer. If you’re late, scalp the weedy lawn, rake away all the debris, and spread grass seed. Some weeds will germinate and grow with the grass, but you can control them using a post-emergent herbicide before they spread further. Weed and feed lawn products combine a lawn fertilizer with a weed killer and/or weed preventer in one product. Different turfs call for different types of products, and application timing is critical. Check out these tips for before and after application for lawn weed and feed fertilizer. When is the best time of year to seed your lawn? What is the worst time of year to seed? Check out this blog post to learn more.
Overseeding a Lawn with Weeds: Should You Kill Weeds First?
A lawn full of weeds can become even more problematic if you don’t overseed the right way. Overseeding is meant to renew your lawn, fill in any bare spots, and make the turf dense. But, when your lawn is full of weeds, should you go ahead and overseed without killing weeds first?
Overseed your lawn in the fall after killing weeds in late summer. If you’re late, scalp the weedy lawn, rake away all the debris, and spread grass seed. Some weeds will germinate and grow with the grass, but you can control them using a post-emergent herbicide before they spread further.
It is not a good idea to plant and grow new grass over weeds because weeds compete for nutrients and water in the soil, which leads to poor germination and growth of the newly planted grass.
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Should I Kill Weeds Before Overseeding?
Kill and remove weeds from your lawn at least 6 weeks before overseeding if you’re using a post-emergent herbicide. Alternatively, remove weeds by hand-pulling manually. Weed killers will affect the seed germination, so, allow enough time as indicated on the product label before planting grass seed.
Since the best time to overseed most lawns is fall, late summer is a good time to put down a post-emergent weed killer. By the time fall comes, it will be at least 4-6 weeks since you applied a weed killer, which is safe for planting grass seed.
How to Overseed a Weedy Lawn
It is best to kill weeds first before overseeding.
Weeds like bare spots and can continue to spread and invade your lawn if you don’t do anything about them. That’s why overseeding helps control them by making your lawn thicker and fuller, and able to choke out weeds.
Overseeding is time and cost-effective, as you don’t have to till and tear apart your lawn. Instead, you’re breathing life back by adding more grass seeds on top of an existing lawn. If done right, this technique lets you grow enough lush lawn that fills in the bare or thin patches in your yard, leaving no room for weeds to grow.
Here’s how to overseed a lawn with weeds:
1. Pull out the weeds manually
Remove weeds from your lawn manually using a weed puller. Pulling weeds out by hand is highly recommended especially if the weeds are grown and visible. Do not apply herbicides on your lawn before overseeding as this can cause poor germination of grass seed.
If you prefer using a weed killer before overseeding, do so early enough to allow time for the herbicide to break down completely before spreading grass seed. Most pre-emergents and post-emergent herbicides have indicated waiting periods before you plant grass seed.
Here’s how to pull out weeds by hand:
- Water your lawn deeply to make the soil soft.
- Pull out weeds by hand or using a weed puller.
- Throw the weeds away from your yard.
In some cases, you may not need to apply a weed killer as weeds like crabgrass usually die off as the weather becomes cooler. If you have annual weeds, just overseed your lawn with weeds late in the fall and allow the new grass to grow. By the time spring comes, your lawn will grow thick and full enough to choke most annual grassy weeds.
2. Mow the lawn on the lowest setting
Set your mower to the lowest setting possible in order to scalp the lawn you want to overseed. Scalping your lawn helps improve the seed-to-soil contact that in turn improves the rate of seed germination. Set your lawn mower’s deck as low as possible – though any setting between 1.5 and 2 inches would be a good option to consider if the lawn does not have too many weeds.
- If your lawn is level, you can set the mowing deck as low as 1 inch from the ground.
- If your lawn is bumpy, set the blades a little higher – up to 2 inches to prevent damaging the blades.
Pro tip: Always bag clippings if your lawn has weeds that have gone to seed to prevent spreading weed seeds all over your yard and worsening the problem.
It is also a good idea, in my experience, to mow right before the rainy week to keep the lawn moist. It makes my mowing job a lot easier as the grass is soft and the thatch easy to remove right before overseeding weedy lawns.
3. Remove grass clippings
Use a rake to remove grass clippings and other debris that’s covering the soil. The process of raking also helps loosen up the top soil in your yard.
If you mowed a little higher, you might have a lot of thatch remaining on the soil surface. Use a heavy duty rake to remove any debris that can prevent your grass seed from staying in contact with the soil for germination.
A good rake can also help you remove any moss that may be growing under the grass in your lawn.
4. Dethatch the lawn
A thick layer of thatch can also cause seed to soil contact problems. Use a dethatcher to break down the thick thatch and then collect the loosened-up trash bag and throw it away on your compost.
Alternatively, run a power rake all over the weedy lawn to loosen up any thatch and tangled-up grass.
When I have a large weedy lawn to overseed, I find it helpful to rent a slit seeder to complete the task in the shortest time possible.
5. Aerate the lawn
By the time it is fall, the soil is usually compacted already, which is why the grass in your yard is growing slowly while the weeds grow faster. After removing the weeds, mowing, and dethatching, core aerate the lawn to allow air, water, and nutrients to be easily accessed in the root zone.
The cores created in the yard will also allow for better seed-to-soil contact as soon as you overseed. This process is better than just sprinkling grass all over the lawn because it improves the rate of seed germination.
6: Spread the grass Seed
Spread grass seed over the prepared area using a lawn spreader. Follow the recommended spreader settings for the type and variety of grass seed you’re overseeding your lawn with to ensure you’ve put down enough make your turf thick and full the next season.
Pro tip: Spread a thin layer of straw to cover grass seed and prevent birds from causing damage. You can also use bird deterrents if you don’t want to cover the grass seed.
For the best results, plant one-half of the grass seeds in one direction and the other half in the opposite direction. I recommend using a lawn spreader for even distribution of the seeds.
Also, you need to make sure the seeds have a good contact with the soil because this helps with proper germination and enhances growth. You can use a water-filled roller or the back of metal rake to establish the recommended contact between the soil and your grass seeds.
7. Gently rake in the grass seed
Raking is important as it helps the seeds come into contact with the soil to germinate properly. If you used a spreader or simply broadcast the seeds with your hand, the grass seed isn’t in proper contact with the soil.
Lightly rake in the seed over the overseeded area to improve contact and promote faster germination. Raking will also prevent water from washing away seeds in your lawn when you irrigate.
8. Water your overseeded lawn lightly
Water the overseeded area lightly to keep the soil moist enough for the grass seeds to germinate and grow. Do not use a heavy sprinkler because it can easily erode the seeds away from the desired area.
Here’s a video on how to prepare and overseed a lawn with weeds:
How to Control Weeds after Overseeding
Weeds may sprout in your lawn soon after your grass seed starts to germinate. At this time, do not apply herbicides yet. Applying herbicides too soon can kill or weaken the young grass shoots.
Wait until the roots have established and the crown matured enough to withstand the strength and effect of the chemicals.
Also, instead of using equipment such as a power rake, which disrupts lawn surfaces, use less disruptive tools such as a hand rake, as they cause less disruption and don’t leave bare patches on the lawn.
Overseed your lawn at the right time to reduce weed competition and enhance the dramatic, successful growth of the overseeding process. You can overseed cool season turf grasses between mid-August and mid-September as a way to fix a weedy yard. These are favorable times for their germination and establishment.
Can I overseed after weed and feed?
It is not recommended to overseed your lawn after applying weed and feed fertilizer. This type of lawn food contains herbicides that can inhibit germination of both grass and weed seeds. If you’ve just put down weed and feed, wait at least 6 weeks before sowing grass seed.
Read the weed and feed product label for the recommended time to wait before reseeding your lawn. Follow the instructions to ensure you achieve a high germination rate when overseeding a weedy yard.
While fall is the perfect time to overseed your lawn and encourage weed control, there are other seasons to overseed provided you understand the risks.
You can overseed in the early spring, but make sure the lawn is well drained for the best results. Weed competition is more progressive and intense as spring progresses. So unless you time the overseeding period before weed germination in spring, doing so at this time may not be effective.
Summer is the least desirable time to overseed your lawn especially if it has weeds. In early summer, the conditions are so hot that there’s a huge demand for irrigation for proper overseeding to be possible. This is also the time when broadleaf weeds tend to thrive, and therefore your overseeding efforts are likely to fail.
Overseeding will make your lawn fuller, and thicker; and improve its pest, disease, and weed resistance. Remember, care for and maintain your lawn after reviving its look and density. Some tips include sufficient watering, proper fertilization, consistent weeding, foot traffic control, and proper mowing.
Weed And Feed Lawns: Where To Begin
Weed & Feed products combine a lawn fertilizer with a weed killer and/or weed preventer in one product. One application does double duty, treating random weeds spread across an entire lawn while also feeding and greening grass. Weed & Feeds come in two basic formulations, granules and liquids. But before you make an application, here are some things you need to know about weed & feed products.
Weed & Feed Starts With Weeding…
The “weed” half of “weed & feed” contains some mix of herbicides to kill lawn weeds. Almost all products contain a post-emergent herbicide, but some also combine a pre-emergent herbicide designed to prevent new weeds from sprouting.
Post-Emergent herbicides kill existing lawn weeds like Dandelion, Clover and many other common weeds. The complete list of weeds can be found on your product’s label. These post-emergents are always selective herbicides, so they will not harm existing grass when applied as directed. New innovations, like BioAdvanced 5-in-1 Weed & Feed, also kill grassy weeds like Crabgrass, eliminating the need for multiple applications of additional herbicides to achieve control.
Pre-Emergent herbicides are meant to keep new weeds from germinating and growing. Timing is the key, apply too early and the preventer can become ineffective while weeds are still dormant. Apply too late and seeds may have already germinated. You’re probably most familiar with Crabgrass preventers that are applied in early spring.
…And Ends With Feeding
The “feed” half of “weed & feed” is all about fertilizer. Most fertilizers are a mix of nitrogen and other macro-nutrients, and sometimes micro-nutrients, in varying amounts. Nitrogen (N) is the most important element in lawn fertilizers and comes in two basic forms – fast-release and slow-release. Most lawn fertilizers include a mix of fast-release and slow-release forms to provide quick green-up and sustained growth.
Fast-Release Nitrogen (often referred to as water-soluble nitrogen or WSN) such as urea and ammonium sulfate, is readily available and absorbed quickly by the grass, resulting in fast green-up. Unfortunately, it can also can burn your lawn if applied improperly, and can leach through the lawns root zone or run off the lawn in heavy rain, causing pollution.
Slow-Release Nitrogen (often referred to as WIN or water-insoluble nitrogen), such as sulfur-coated urea, methylene urea and animal manures, are released more slowly to the grass and provide more sustained, even growth – up to 3 months for methylene urea.
Before You Begin, Know Your Lawn Type
Before applying any type of weed & feed or fertilizer product, you need to identify your type of grass. Some fertilizers can be applied to all lawn types, but most weed & feed products are specifically labeled for certain types of grasses. Apply the wrong product to the wrong type of grass and you can damage your lawn. Use caution and read the label. If you’re still unsure, use the toll-free number found on the label to contact the manufacturer.
When To Apply
Weed & Feed products are most effective when weeds are small and actively-growing, namely spring and fall.
In spring, wait to apply until you’ve mowed your lawn two times before applying to be sure it has emerged from dormancy.
In fall, be sure to check the with local Cooperative Extension System office for historical frost dates in your area. Many Weed & Feed labels will recommend application timing based on that date.
Most weed & feed products will have temperature restrictions as well, be sure to check the label. Do not apply to water-saturated soils, lawns under stress from drought, disease or prone to injury.
How To Apply
For liquid weed & feed products, be sure to use one of the sprayer types recommended on the label and follow label instructions for mixing and spraying.
For granule weed & feeds, use a rotary or drop-type spreader. Drop spreaders apply fertilizer very precisely in a narrow band directly below the spreader, while a rotary spreader broadcasts over a wider area. The application pattern is very important. Be sure to follow label instructions.
Both types of spreaders have adjustable application settings. How much fertilizer is applied varies according to the settings on the type and model of spreader you use. Read the spreader manufacturer’s instructions before fertilizing to help you calibrate your equipment to ensure proper application rates. You’ll find the proper setting for your type of spreader on the specific fertilizer label. If not, there should be a toll-free phone number to call. Do not use the spreader until you are sure it is set properly. You can learn more about calibrating your spreader and spreader settings. Be sure to read always and follow label instructions.
Other Things You Should Know
Mowing – For best results, mow your lawn 1-2 days prior to application. Clippings from your next three mowings should be left on the lawn. Be sure not to use these clippings as mulch or compost around flowers, ornamentals, trees or in vegetable gardens.
Do Not Rake – Heavy raking will disturb the weed preventative barrier and reduce the effectiveness of this product.
Watering – Many weed & feed products instruct you to wait 24 hours before watering in. Be sure to consult your specific label.
Feeding New Lawns – Most new lawns don’t need to be fertilized until 6-8 weeks after planting. However, that can vary depending on how the soil was prepared before planting and the type of fertilizer used. Consult your local Cooperative Extension System office or nursery for recommendations on fertilizing new lawns.
When is the best and worst time to seed your lawn?
When is the best time of year to seed? What about the the worst time? Here’s the answer from best to worst:
1) Most successful
The last five weeks of summer to early autumn, pending the weather, is the best time of year to seed. At this time, day and nighttime temperatures are cooling, dew is more present on lawns, and annual broadleaf weeds and crabgrass are dying. This means new turf can easily establish with little to no competition. If you’re going to seed, this is absolutely the best time of year to do it. Don’t miss your opportunity otherwise you’ll be waiting an entire year for the next window to open.
When you do seed, watch it closely. Kentucky bluegrass mix can take upwards of 4 to 6 weeks to fully emerge while perennial rye can take 1 to 2 weeks. If you seed during drought conditions, and the seed doesn’t take, don’t hesitate to seed again. Getting something established before the ground freezes is paramount and will make a big difference in what you’re able to do with the new turf the subsequent spring. The thicker your turf is in the fall, the better it’ll hold crabgrass pre-emergent the following year.
By mid-October your window to seed is usually rapidly closing. A mixed bag of seed or hydroseed can take upwards of 4 to 6 weeks to emerge and establish itself to the point that it’s able to survive the winter. Remember, at this stage in the turf’s life it’s not all about the blade…it’s about its root system. The harder the soil (due to it being frozen) the more difficult it is for roots to penetrate deep underground. At this time of year use perennial rye grass, which grows faster.
3) Early spring
Early spring is second to last on this list for a few reasons. Yes, the seed is likely to grow just fine because of the typically wet, cool weather. However, here’s the caveat: Under many circumstances, pre-emergent crabgrass control and broadleaf weed control will negatively impact the new turf. It can also be challenging to near impossible to keep young turf alive through the brutal New England summer. We do not recommend aerating and overseeding (or renovating) an entire lawn at this time of year. While aerating is beneficial, the process can actually pull weed seeds from the soil depths to the surface, exacerbating weed problems. However, if you want to patch up a few small spots, this may be a fine time to do so.
4) Late spring (May/June) – late July/early August
There is little to no long-term success when seeding an entire lawn or large sections of your property at this time of year. Doing so could set your lawn back a few to several years. You’ll be constantly battling crabgrass and weeds.
If you’re overseeding, keep the following in mind:
- Always aerate before you overseed. The seed germinates in the plugged holes which presents a cool, wet, soft, and favorable growing environment. Little to no seed establishes when placed directly on top of soil that hasn’t been cultivated.
- It may take upwards of 2 to 3 years to see the full results from a single aeration/overseeding as new grass emerges from the holes and the canopy of already existing turf thickens.
- If you’re patching up small areas of your lawn, loosen up existing soil and apply top soil. This will give the new seed a better chance to take root. Otherwise, it’s like trying to plant grass on concrete.
- Just because new seed emerges in the fall it doesn’t mean it’ll survive the following year without proper care. For example, if you forget about it several months later, it’s very unlikely to make it through the summer. This turf needs to stay well-watered and manicured.
- It’s not uncommon to have to seed areas of your lawn that succumbs to summer heat or general wear and tear. Adhering to the tips presented here will give your lawn the best chance of success.
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